The council is providing the airline with a 475,000-euro subsidy to provide the services for three years in an initiative aimed at bolstering tourism in the isolated Auvergne region.
Northern Portuguese city Porto was chosen as a destination because Auvergne has a large Portuguese community while Charleroi, in southern Belgium, is a hub for Ryanair.
The budget airline announced on Wednesday it was returning to the Strasbourg-Entzheim airport in eastern France after a 10-year absence
triggered by the withdrawal of subsidies it was receiving from the city's chamber of commerce.
The airline will resume operations from Strasbourg in northeastern France in April 2013 with flights to London Stansted three days a week and to Porto on two days.